Starting and operating circuits for fluorescent lamps



April 1956 w. s. H. HAMILTON 2,743,383

STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS 2 Sheets-Sheet 1 Filed Nov. 4, 1952 51 ICE/(QC INVENTOR! W/Y/Ia/n 5. /7 Ham/W0!) ATTORNEY.

April 1956 w. s. H. HAMILTON 2,743,383

STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS Filed NOV. 4, 1952 2 Sheets-Sheet 2 Q- ZH- BY ATTORNEY United States Patent STARTING AND OPERATING CIRCUITS FOR FLUORESCENT LAMPS William S. H. Hamilton, Larchmont, N. Y. Application November 4, 1952, Serial No. 318,609 6 Claims. (Cl. 315-100) in part of my prior June 6, 1951, now

and magnetic starting contacts and a magnetic coil, the

combination being so arranged that when the thermal starting contacts open, the coil is energized by the preheating current through the lamp filament or filaments to cause the magnetic contacts to be opened very rapidly to start the lamp, the coil thereafter remaining in series with the lamp while the lamp is operating, holding the magnetic starting contacts open by magnetic means and the thermal starting contacts open by means of an insulated mechanical interlock connected to said magnetic contacts, thus allowing cooling of the heater for the thermal starting contacts without permitting the thermal starting contacts to reclose, the circuits including reactance means for giving an inductive kick when the magnetic starting contacts open, whereby the lamp, if in normal condition, will fire and the lamp will operate until the line voltage is interrupted when the coil will be deenergized and both starting contacts will immediately reclose, enabling the lamp to restart without delay upon another application of line current.

The primary object of the invention is to provide in a starter embodying these features current actuated means for automatically cutting out or locking out the starter in the attempted starting of a defective lamp or one which has passed its'useful life period, in order to prevent injury to the starter or other components of the circuit.

' Another object of the invention is to provide a starter which may be reversible in its socket.

A, further object is to provide a starter which will prevent the annoying ghost lighting," objectionable in the use of certain types of long lamps when cut out of action by conventional starters now used.

The invention will be understood from a consideration of the accompanying drawings and the following detailed description.

In these drawings:

Fig. l is a diagrammatic view of a circuit for D. C. lamps employing a reactor and a starter embodying my invention, said starter including a quick restarter as Well as a cut-out or lock-out means of the character re ferred to. v

Fig. 2 is a diagrammatic view of a circuit similar to that of Fig. 1 but adapted for A. C. or D. C. use.

Figs. 3, 4 and are schematic obverse, reverse and side elevational views of a starter embodying the quick restarter and the cut-out or'lock-out means, showing only the basic featuresof the starter and omitting the wiring connections.

Figs. 6, 7 and 8 are diagrammatic views showing further modified circuit arrangements for D. C., A. .C., or D. C. and A. C. use, respectively, restarting and cut-out or lock-out means of the character described, which lock-out means when operated disconnects one line terminal from the lamp to prevent ghost lighting.

In the schematic showing of the starter in Figs. 3, 4 and 5, A designates an insulated base carrying contact pins 1, 2, 3, 4, and an insulated upright A", which in practice are enclosed in a housing or casing, not shown. On this upright are mounted a relay coil C, tracted relay armature switch S1, two thermally responsive or thermostatic switches S2, S3 H3, for the switches, which are connected in the manner shown in those circuits employing the switch S3 and its heaters, H2 and H3 for a lock-out action, which switch and its heaters may be omitted from a starter designed for general use but used most commonly in circuits not employing a lock-out action, the inclusion or omission of such switch and its heaters involvingmerely changes in the wiring arrangements.

The switches, which are of self-closing type and nor mally closed are not physically coupled for conjoint action,

but are independently movable, switch S1 under action of the coil C and switches S2, S3, in response to their heaters, with the exception that a quick restarter in the form of a mechanical interlocking connection (controlled by the armature actuated by the coil and generally designated MIC in the drawings) is interposed between switches S1 and S2, and is provided for holding switch S2 open together with switch S1 under the electro-magnetic attraction of the coil C when the latter is energized. Coil C when energized acts only to pull switch S1 open after switch S2 has been thermally opened, and in such action moves the interlocking connection into position to hold switch S2 in its open position.

This connection comprises an insulated arm A4 carried by the armature switch S1 which normally allows full opening movement of switch S2, but which moves into engagement with switch S2 when switch S1 is opened to hold switch S2 open, this holding action being due to the magnetic attraction of the coil. A condenser C omittedin Figs. 3, 4 and 5, but shown in the lamp circuits, is included in the starter to reduce the arcing at the con tacts in accordance with customary practice. A stop A5 is provided to limit the travel of thermal switch S3 when heated.

In the drawings I have shown five types of circuits'for fluorescent lamps as examples of types in which the starter A, in the forms disclosed, or by simple changes in the wiring or arrangements of parts, may be used to secure prompt and reliable starting actions of a lamp in good order and which may be used to secure a cut-out or lockout action to avoid undue repetitive starting attempts if the lamp is defective or has reached the end of its useful life period.

Referring now to Fig. l of the drawing, circuit for operation of lamps on D. C., 5 designates the lamp having a filamentary electrode 6 adapted to be preheated and a cooperating electrode 7 which, as shown, is openecircuited, and S and 9 designate the input and output line leads extending from the line terminals to the starter contact terminals 1 and 3 through which current is supplied to the lamp. The circuit includes a reactor R arranged in conductor 8 ahead of the starter terminal 1 and a branch'14 connecting it therewith, a branch conductor 8 leading from the conductor 8 at a point betweenthe reactor and terminal 1, to one terminal of the electrode 7, a'ballast lamp BL in the conductor 8 and a preheating conductor 10*, containing a current limiting resistance R1, leading from the starter contact terminal 2 and each embodying quick a spring reand heaters H1, H2 and.

showing a to the input end of the electrode 6, from the output end of which the negative return conductor 11 leads to the starter contact terminal 4. Conductors 8, 10 11 and 9* form with their component parts and cooperating parts of the starter per se a. lamp preheating or starting circuit while conductors 3, 8 11 and 9* form with the electrodes and cooperating parts of'the starter per se an operating circuit for the lamp.

The starter switch circuit arrangement as shown in Fig. 1 comprises input conductors 12 with the terminals 1 and 2, output conductors 15, I5 connected with the terminals 4 and 3, a relay switch S1 normally connecting the output ends of conductors Il 13, a relay coil C connected in series with the terminals 3 and 4 between, the conductors 15 15, a thermostatic time delay switch S2 normally connecting the conductors 15 15 and extending across the coil C, a thermostatic cut-ont switch, S3 connecting the input end of conductor 12? with. the. terminal 1, a heater Hi for the. switch S2 arranged. in. conductor 12, a heater H2 for the. switch S3- connected between and in series with said conductor 1'2 and switch. S3 when the latter is closed, and asupplemental or auxiliary heater H3 for the switch S3 connected in conductor. 12! between the terminal 1 and heater H1 across the switch S3, a mechanical interlocking. connection MIC of the type described, and an arc, suppressing condenser C" connected between terminals 1 and 2, by which connection it serves to suppress arcs, upon the. opening of either magnetic switch. S1 or thermal switch S3.

With the parts normally arranged, asjshown in, Fig. l the switches S1, S2, S3 and heaters, H1, H2 are connected in series with eachv other and with the electrode 6 and line conductors to form a closed preheating circuit to preheat the electrode when for a lamp starting operation, during which, time a bypass is formed by, the conductors 15,, 15 and. closed. switch S2- which shunts the, coil C out. of the path of flow of the preheating current sothat, it remains de-energized until the switch S2 opens and breaks. the shunt across. the coil.

Heaters H1, H2 may. be open coil heaters of. suitable. resistance, heater H2 being of such resistance andso located that the current flowingthrough, it. will. notheat it enough to cause thermal $WitchS3 to open. its'contacts during a normal starting action, but, repetitions. of. start.-

ing actions, such as. occur with a, defective. lamp orone which has reached the. end, of itsuseful life, will heat heater H2. sufliciently so that. it. will. cause-switchss to open its contacts. Heater resistor, is of high resistance as compared with heaters H1, 112., but. it is so arranged, that. once. the. contacts. of thermal switch. S3 have opened, it. (heater H3.) will have substantially, line voltage applied. across it. to. keep. the contacts ofthermal switchS3' open.

The circuit, construction. described adaptsit'to be. used. with a starter having only four contact. terminalsand applicable to a lamp starter. socket ofconventional type.

In this circuit when starting, through the reactor to terminal switch S3,. heaters, H2v and H1, through switch. S1 to terminal 2 of the starter, through resistanceRl, through the negative filament 6 of the latngto tcrmi'uab4v of the starter, through thermal switch. S2.v to terminal 3 back to the negative side. of the line. Heater H2 as. described above, is. of. relatively.

of the. starter, and thence low resistance, but is. so proportioncdand so. located with respect to heater H1 that it. does not. act. as. quickly. on

thermal switch S3, as heater. H1 does on thermal switch. S2. Therefore, no part. Heater H3. is a normal-starting action. I

The. flow of preheating current continues until: heater H1. has. heated2 sufiiciently. to. cause open its. contacts. When they open,

effectively short-.circuited during 13* connected. I

the. line, circuit is, closed.

H32, whichmay be a carbon preheating. current flows. 1 of the starter, through;

during a. normal. starting action it plays. F

thermal switch S2. to they cut coil Qinto.

the preheating circuit. This causes the coil to open switch S1 by magnetic action and break the preheating circuit through the lamp rapidly. This causes the lamp, if in good condition, to fire, and after it has fired, operating current flows from the positive side of the line through the reactor, through the ballast lamp, to the positive filament 7 of the lamp, through the gas in the lamp itself to the negative filament 6, thence to terminal 4 of the starter, through coil C to terminal 3 of the starter, and thence to the negative terminal of the line. Coil C being energized, holds switch S1 open by magnetic action, and by means of the mechanical interlock MlC also holds the contacts of thermal switch S2 open. after the heater H1 cools off.

If while the lamp is operating normally, the line circult is opened, coil C immediately allows switches S1 and S2 to reclose, so as to be ready for another starting action uponthe line circuit being recloscd.

A normal starting action does not heat heater H2.

sufficiently for it to have effect enough on thermal switch S3 to cause it to open its contacts, and once the lamp has fired, all heat is removed from heater H2.

Should the. lamp fail to start, however, it will make several attempts to do so. and each time the heat in heater H2 is increased, until it heats up sufliciently to cause thermal switch S3 to open its contacts. The open ing of switch contacts S3 cuts current oil the lamp and also connects heater H3 substantiallyacross the line. H3 is of high resistance but of sufiicient capacity to keep thermal switch S3 open. Switches S1 and S2 reclose under this condition. The. only current flowing through the circuit is the. small amount through heater H3.

In a circuit embodying the multiple action lockout feature above described, an appreciable. time delay (several minutes) will be required. when the line circuit is opened for heater H3 to cool sufiiciently' to allow thermal switch S3. to reclose its contacts, so that the starter is ready to restart a lamp. This timedelay can be avoided, however, by replacing the defective fluorescent lamp and thestarter at the same time. The starter can then be used in some other circuit later, as it will not have been damaged inany way.

Figure 2 shows an operating circuit suitable for A. C. or D. C. fluorescent lamps and which also has the multiple action lock-out feature, and in which the arrangement of theparts of the starter are the same as in Fig. 1, but the circuit varies from that shown in Fig. l in that one line conductor 8 containing the reactor R and the ballast lamp BL is connected by a conductor 8 with one terminal of electrode 7, the other terminal of which is con nected. by a conductor 10 with starter terminal a, conductor 10 containing a current limiting resistance R1, connects. the starter terminal 1 with the input terminal of. electrode 6, thus connecting both electrodes for a preheating action in series with the line through the starter. The. ballast lamp used in this circuit can be omitted if the other requirements of the circuit permit it.

In this circuit when starting, preheating current flows from one side 8 of the line through the reactor, through the ballastlamp, if used, through filament 7 of the fluorescent lamp to terminal 2 of the starter, through switch S1, heater H1, heater H2, thermal switch S3, to terminal 1 of the starter, through resistance R1, through the other filament 6.- of the fluorescent lamp to terminal 4 of the starter, through thermal switch S2 to terminal 3 of the starter, and thence to the; other side. of the line. The; action both. in normal starting and; in cut'out actionsis substantially the same as .described with respect to: Fig. 1,, except that both filaments. of the. lamp. are used in starting, and will be, apparent, therefore, not be described. in

detail. a

Fig, 6.shows.a circuit, arrangementand starter, similar to thatof. Fig. l, for use on D. C. in which thestarter in, cut-outposition efiectively opensthe, connectionbetween one line terminal and the lamp in order to. elimirent values and prevent what is known as ghost lighting due to this cause, while Fig. 7shows a circuit arrangement andstarter similar to that of Fig. 2 in which the starter in cut-outposition acts in the same manner to prevent ghost lighting.

In each of these circuits the starter varies from those shown in Figs. 1 and 2 in that the switches S1 and S2 are connected in a different manner in the starter circuits, the principal difference being in the arrangement of the wires 12, 12 and 15 which in Figs. 6 and 7 connect heaters H1, H2 in series with switch S1 between starter terminals 1 and 2 and connect switch S3 and heater H3 in series in the circuit connection between switch S2 and the line instead of that between switch S1 and the line, as shown in Figs. 1 and 2, so that switch S3 is connected directly with the starter terminal 3. By this arrangement connection to one side of the line is positively broken when switch S3 opens, as heater H3, which still connects the lamp to the line after switch S3 opens, will not pass enough current to cause ghost lighting.

Fig. 8 shows the starter as designed for use with the long 48", T-12 lamps used largely in industrial lighting applications. The use of a cut-out feature operative in its cut-out position to disconnect one line terminal from the lamp to prevent ghost lighting due to lamp discharge at low current values, as above described, is more necessary with long lamps of the 48", T-12 type than with shorter lamps operated on A. C. or D. C., as such long lamps are especially subject to the objection mentioned on account of the high voltage impressed on them.

The circuit design shown in Fig. 8 is one in which a reactor-transformer R-T is connected by its primary across the line and by its secondary with conductor 10 leading from one side of the line to the input terminal of electrode 6, whose output terminal is connected by conductor 11 with the starter terminal 2 and connected in series through the starter and conductors 10 10 with starter terminal 3 and conductor 9 leading to the other side of the line, the elements of the starter shown in Fig. 8 being the same in construction and arrangement as that shown in Figs. 6 and 7.

The operation of the circuit and starter arrangements shown in Figs. 6, 7 and 8 is substantially the same as that described with respect to Figs. 1 and 2, with the exception of the above-described line cut-out action of switch S3, so that a detailed description thereof is unnecessary.

Switch S3 in the circuits of Figs. 6, 7 and 8 has a desirable function, in addition to that of effecting the lock out action. While lamps of the 48", T-l2 type allow operation of a lock-out starter into lock-out position after they have reached the end of their useful life, they may still continue to pass current at a low value unless one filament is disconnected from the line, which is not effected at all or with certainty by many starters of this type in general use. This low current passage usually causes flickering or ghost lighting which is annoying and objectionable. My improved type of starter effectually overcomes this objection in an obvious manner.

A starter embodying the present invention has the following two major advantages over prior starters, to wit, (1) the preheating or starting circuit is broken rapidly by the opening of switch S1 by magnetic means. This causes the reactor to give a higher inductive kick than that obtained from the slower opening of straight thermal or glow switch starters when used in the same circuits. The higher inductive kick not only makes the firing more certain, but will also effect the firing of lamps that might be discarded under the impression that they had reached the end of their useful life period. (2) In all normal operation of the lamps, due to the switch S1 being held open magnetically by the coil C by the flow of current through the lamp, the switch will open immediately if the line circuit is opened, and in so doing allow switch S2 to also reclose, so that the starter is ready for another starter action as soon as the line circuit is reclosed. This is not so in the case of a straight thermal starter, where it is necessary for the heater to cool off before its contacts can reclose.

(3) If the lamp fails to start after a number of actu-: ations of the starter the cut-out switch, initially actuated by the'preheating current, and held in the cut-out or open position by a high resistance heater connected sub stantially across the line by the opening of the cut-out switch, effectively prevents further actuations of the starter and, if desired, also disconnects one terminal of the lamp from the source of line voltage.

From the foregoing description, taken in connection with the drawings, the construction and operation of the starter and circuits disclosed will be readily understood without a further and extended description, and it will be seen that the invention provides a starter of simple and economical type which facilitates and renders easier the starting of hard starting lamps, and one which provides means for securing a quick restarting when desired and means for locking out the starter from continuous or undesired repeating actions to prevent damage to the starter or other components of the circuit in the case of a defective lamp, or a lamp which has reached the end of its useful life. While the constructions shown for these purposes are preferred, it is to be understood that they are merely exemplificative, and that changes in the form, construction and arrangement of parts, falling within the scope of the appended claims, may be made without departing from the spirit of the invention.

Having thus described my invention, I claim:

1. In a system for starting and operating an electric discharge device comprising a gaseous electric discharge device having at least one electrode constructed to receive preheating current, a normally closed electromagnetic switch and a normally closed time delay thermostatic switch having an operating heater, means including an inductance device and the winding of said electromagnetic switch for connecting said electrodes with a source of current supply, a preheating circuit capable of producing firing temperature electrode heating, said circuit extending from one side of said supply source to the opposite side thereof and including in series connection said inductance device, said electromagnetic switch, the heater for said time delay switch, said winding and at least one of said electrodes, said time delay switch being connected across said winding so that the opening of said switch introduces said winding into the preheating circuit and causes rapid opening of the electromagnetic switch to cause the discharge device to fire by an inductive voltage kick, and mechanical means operatively interconnecting said electromagnetic switch and said time delay thermostatic switch to hold said latter switch open after the heater therefor cools, the operating current of said device continuing to energize said winding and hold both of said switches open during the operation of the device, and, should the device not fire, said electromagnetic switch continuing to open and close thereby repeatedly attempting to cause the device to fire, the combination of mechanism operative after several such actuations of said switch to prevent further actuation thereof comprising a cut-out thermostatic switch having main and auxiliary heaters, said switch and main heater being connected in series in the preheating circuit, and said auxiliary heater being connected in a circuit which is connected across said cut-out switch so that after the several actuations of said electromagnetic switch the cut-out switch is opened by the heat from said main heater, said switch being thereafter maintained open by heat from said auxiliary heater, said auxiliary heater having a resistance value which limits the current through the preheating circuit auzgssa to a; magnitude insufficient toopen said'electromagneti'c. switch,

2;, A. system for starting and operating a-gaseous electric discharge device as; claimed in claim I in whichv both electrodes; oi the discharge device. are included in the preheating circuit.

3. A system for starting and operating a gaseous electric discharge device". as, claimed in claim 1 in: which the cutrout switch. is. connected in that. portion 05 the: preheating circuitwhich is between one of the ele'ctrodesrand' onesidc of the supply source sothat. the opening of said switch: disconnects saidt electrode from the supply source.

4. In a: system. for starting and operating an electric discharge, devicecomprising. at gaseous: electric discharge. device having two= electrodes, at least one of which is constructed to receive preheating clurent, a normally closed electromagnetic switch and a normally closed: time delay thermostatic switcha having-ancoperating heater, an inductance device, one-of saidelectrodes; being connected to; one side of a: source, ofi current, supply through the windicgof said electromagnetic: switch and: theother elecmade being connected to the; opposite side ofv said source through said inductancedevice, apreheating. circuit capabio of producingfiring temperature: electrode heating, said circuit extending from one side of; said supply source and including in series connection said inductance device, said electromagnetic switch, the heater for said time delay switch andat least one oi said electrodes, said circuit continuing through said winding, to the opposite side of said current supply, said time delay switch being con nected across said winding so that the opening of said switch introduces said winding into the preheating circuit and causes rapid opening of the electromagnetic switch to cause the discharge'device to fire by an inductive voltage kick, terconnecting said electromagnetic switch and said time delay thermostatic switch to hold said latter switch open and mechanical means operatively in- 35 after the heater therefor eools' the operatingcurrent' ofi said: devicecontinuing to: energize said winding andhold both of. snid'switehes open during the operation of the device, and, should the device not fire, said el'ectroma-g netic switch continuing to: open and close thereby re peatcdly attempting to cause the device tofir-e, the corn hinati'otr of mechanism operative after severalsuch actuations: of said switch: to prevent" further actuation thereof comprising a. cut-out thermostatic switch having main and auxiliary heaters, saidi switch: and main heater being connected in series iii-the preheating circuit, and said auxiliary heater being connectedi'n a circuit which is connected. across said cut-out switch so: that after the several actuations. of said electromagnetic switch the cuti out switch: isaopenedi by the heat from said main heater,

said switch being thereafter maintained open by heat from said auxiliary heater, said auxiliary heater having a resistance value which limtsthe current throughthe preheating circuit to a magnitude insuflicient to open said electromagnetic switch.

- 5. A system for starting and operating a gaseous-elec tric discharge device as claimed in claim 4 in which both electrodes 05 the discharge device are included in. the preheating circuit.

6. A- systcrn for starting and operating a gaseous electric discharge device as claimed in claim 4 in which the cutrout switch is connected in that portion of the preheating circuit which is-between one of the electrodes and one side of the supply'source' so that the openingof said switch disconnects said electrode from the supply source.

References, Cited in the file of this patent UNITED STATES PATENTS 2,3413520- Babb Feb. 15, 1944 2,374,315 Whiteside Apr. 24, 1945 2,476,330. Sitzer July 19, 194-9 

